For carrying out an effective and planned conduct of a herd of cows with the aim of improving milk output, for determining ration and also for commercial deals with the purchasers, it is necessary to have accurate, reliable and objective information on milk outputs.
The main problem in accurate metering milk at dairy farms is the disagreement between mathematical and physical models of the process of metering of milk output which is caused by differences between ideal and real operating conditions and by the influence of milk properties on accuracy of measurements.
In addition, properties of the fluid being measured--milk--are unique and feature a large scatter of parameters. Specific features of functioning and operation of specific types of milkers and milk meters used also have a substantial effect on accuracy of measurement of milk outputs in milkers so that milk meters should be individually adjusted for optimum metering during milking by milkers. Conventional techniques aimed at enhancing accuracy of metering of milk outputs by optimizing design of a metering chamber of milk meters based on milk mass metering, milk level or milk volume metering in the metering chamber cannot be further improved.
Known in the art is an apparatus for automatically metering milk drawn by a milker, comprising a float-type milk meter having an admission chamber and a metering chamber communicating with each other, a float located in the admission chamber, the float with a valve member being mounted on one and the same hollow rod having an opening in the upper portion extending outside the admission chamber and an open bottom end, the rod cooperating with a means for recording milk quantity, and the metering chamber of the milk meter communicating with an evacuated milker pipeline through an outlet pipe (SU, A, 657260).
In this apparatus, when the metering chamber of the milk meter is filled with milk during milking, milk is admitted through an opening in a partition from the metering chamber to the admission chamber. As a result of the rise of milk level in the admission chamber the float with the rod and valve member surfaces to the filling level of the admission chamber, and the valve member shuts off the opening of the partition. The upper portion of the hollow rod protrudes outside the admission chamber, and the metering chamber communicates with atmosphere through the opening and the interior space of the rod. Owing to a pressure differential, milk is displaced from the metering chamber into the evacuated milk pipeline through the outlet pipe. The rod with the float and valve member transmits the float rise force to a recording means which records a batch of milk at the upper point of the rod rise and the rod then moves down under gravity so that the process of metering and recording of individual batches can be automatically repeated.
This apparatus works with a large error of metering of individual milk batches metered by the metering chamber of the milk meter as a substantial error appears in the measurement of individual batches of milk because of a faulty method of contact recording by transmitting mechanical force from the rod after the rise of the float when the chamber is filled up with milk to the milk quantity recording means.
The number of actuations of the valve member provided on the float rod is thus automatically counted, rather than the actual quantity of milk metered by the metering chamber. The ratio of the number of actuations of the valve of the milk metering chamber to the number of batches of the milk cannot be recorded in this apparatus so that accuracy of this apparatus is rather low.
Known in the art is an apparatus for automatically metering milk drawn by a milker--electronic milk meter "Surge" designed for automatic dairy farms controlled by means of an automatic system "Diary Manager", comprising an admission chamber and a metering chamber for milk separated by a partition, a rod carrying a valve member in the metering chamber and a float in the admission chamber, and a counter means for recording milk batches drawn by the milker (Babson Bros. Co. USA. "Surge", 1987).
Individual milk batches are recorded by this apparatus also by means of the valve member in the metering chamber as it is filled up with milk during cow milking. The float acts mechanically upon the counter means of the milk meter thus introducing an error in measurement of individual batches of milk.
Known in the art is an apparatus for automatically metering milk drawn by a milker, comprising a float-type milk meter having an admission chamber communicating with an evacuated milk pipeline through an inlet pipe, the admission chamber and the metering chamber communicating with each other communicating through outlet pipes with evacuated milk collector of the milker which is connected to a vacuum plant of the milker and with a milk pump of the milker, the chambers accommodating a hollow rod having a valve member at the bottom end thereof and a magnet at the upper end thereof cooperating during movement of the rod with hermetically sealed contacts electrically coupled to a digital computer unit for recording quantity of milk drawn by the milker (SU, A, 1345059).
This apparatus takes into account properties of the fluid being metered--milk--by putting coefficients of correction of readings of the milk meter in the memory of the computer unit in accordance with deviations of its actual readings from the reference batch of milk drawn by the milker.
As a result, accuracy of determination of quantity of milk in this apparatus substantially depends on sample size of milked quantity for which the apparatus is adjusted. Since the sample size during the real milking process is always a random value (the total milk output cannot be determined in advance) an error of readings is caused by the difference between the results of accurate adjustment of the apparatus for a preset sample size and the actual sample size of freshly drawn milk obtained by metering individual batches of milk thus lowering confidence of metering and accuracy.